The Anatomy of a Strong Password
What actually makes a password strong — entropy, length, and why complexity rules matter less than you think.
Most people believe strong passwords mean adding exclamation marks and swapping letters for numbers. The reality is both simpler and more interesting: strength comes down to one thing — randomness.
What Attackers Actually Do
Forget the Hollywood image of a hacker guessing your password one letter at a time. Real attacks are automated:
- Credential stuffing — trying passwords leaked from other breaches (the most common attack)
- Dictionary attacks — testing millions of common passwords and variations, like
P@ssw0rd123 - Brute force — trying every combination, only practical for short or weak passwords
Modern cracking tools test billions of passwords per second against stolen hashes. A "clever" human-made password follows patterns, and patterns are exactly what these tools search for.
Entropy Is the Only Real Measure
Password strength is measured in entropy — the number of bits of randomness it contains. Each bit doubles the search space:
- A random 8-character password from all printable characters: ~52 bits
- A random 12-character password: ~78 bits
- A random 16-character password: ~104 bits
The key word is random. Tr0ub4dor&3 feels random but follows predictable substitution patterns, so its real entropy is far lower than its length suggests.
Length Beats Complexity
A famous xkcd comic illustrated this well. Compare:
Tr0ub4dor&3— 11 characters, pattern-based, maybe ~28 bits of real entropy- Four random common words like
correct horse battery staple— 28 characters, ~44 bits from word choice alone
Random words are easy for humans to remember and hard for machines to guess. The randomness must come from a generator, though — your favorite phrase is not random.
The Real Rules That Matter
- Never reuse passwords. A breach at one site exposes every account using the same password.
- Use a password manager. It generates and remembers truly random passwords for you.
- Enable two-factor authentication. Even a stolen password becomes far less useful.
- Length first. When in doubt, go longer, not more "complex."
- Check breach databases. Services like Have I Been Pwned tell you if your credentials have leaked.
Generating Passwords Safely
Any password generator that runs on a server sees your password. A browser-based generator uses your device's cryptographically secure random source (the Web Crypto API) and never transmits the result — the password exists only on your screen.
Try It Yourself
Generate a strong, random password right in your browser with our password generator — built on the Web Crypto API, fully offline, nothing ever sent anywhere.